crystal-cvs (Subscribe, archive at Gmane, archive at SourceForge) receives notifications every time a commit is made to the Crystal Space source repository. Be aware that this are a lot of messages occasionally, but you can keep track of the development very closely.

crystal-tracker (Subscribe, archive at Gmane) receives notifications when a change is made to the Crystal Space issue tracker. This allows to keep track of new bugs and the work on existing ones.

DevMaster.net has a database of graphics engines. Of course, Crystal Space is present there as well (in the category Open Source engines). You can also write reviews for engines and vote for your favorite one (i.e. Crystal Space).